General Chemistry (ATC)

Chemistry begins with measurement and the mole.

• The mole is 6.022×10²³ particles (Avogadro's number).
• Molar mass (g/mol) converts between grams and moles.
• Use the metric system and significant figures.
• Energy is measured in joules or calories.

The periodic table organizes the elements.

• Atoms contain protons, neutrons, and electrons.
• Ions form when atoms gain or lose electrons.
• The table is arranged by atomic number into periods and groups.
• Periodic trends include electronegativity and atomic radius.

Reactions rearrange atoms and involve energy.

• Reactions are balanced to conserve mass.
• Types: synthesis, decomposition, single/double replacement, combustion.
• Exothermic reactions release energy; endothermic absorb it.
• Solutions are homogeneous mixtures with concentration (molarity).

Chemistry quantifies reactions and their rates.

• Stoichiometry relates amounts of reactants and products.
• Kinetics studies reaction rates and factors that change them.
• Equilibrium is when forward and reverse rates are equal.
• Le Chatelier's principle predicts shifts in equilibrium.

Bonds hold atoms together.

• Ionic bonds transfer electrons; covalent bonds share them.
• Metallic bonds share electrons in a "sea."
• Bonding follows the octet rule.
• Bond type affects a substance's properties.

Atomic theory has evolved over time.

• Models progressed from Dalton to Bohr to the quantum model.
• Electrons occupy orbitals and energy levels.
• Electron configuration describes their arrangement.
• Quantum theory explains atomic behavior.

Acids and bases have opposite properties.

• Acids donate H⁺ (low pH); bases accept H⁺ / donate OH⁻ (high pH).
• The pH scale runs 0–14, with 7 neutral.
• Neutralization forms salt and water.
• Indicators and titration measure acidity.

Nomenclature is the system for naming compounds.

• Ionic compounds name the cation then anion (e.g., sodium chloride).
• Covalent compounds use prefixes (mono-, di-, tri-).
• Polyatomic ions have special names (e.g., sulfate).
• Correct naming communicates composition.

Matter exists in states with distinct properties.

• Solids have fixed shape; liquids flow; gases fill their container.
• Physical properties (density, melting point) vs. chemical properties.
• Gas laws relate pressure, volume, and temperature.
• Phase changes occur with energy transfer.

Electrochemistry links chemical reactions and electricity.

• Redox reactions transfer electrons (oxidation and reduction).
• Electrochemical cells produce or use electric current.
• Entropy is a measure of disorder.
• Reactions tend toward higher entropy and lower energy.